Arrangement in speaking radio beacons



5 Sheets-Sheet l INVENTOR CARL-ERIK GRANQVIST Frequency Generator ARRANGEMENT IN SPEAKING RADIO BEACONS June 23, 1964 Filed March 4. 1958 commutator Moton- [7 FIG.

F /6 5 BY 0 mm w W ATTORNEYS:

June 23., 1964 Filed March 4. 1958 CARLERIK GRANQVIST ARRANGEMENT IN SPEAKING RADIO BEACONS a Sheets-Shet 2 INVENTOR CARL-ERIK GRANQVIST BY o w y ATTORNEY 8 June 23, 1964 CARLERIK GRANQVIST 3,138,799

ARRANGEMENT IN SPEAKING RADIO BEACONS Filed March 4, 1958 5 Sheets-Sheet 3 INVENTOR CARL-ERIK GRANQVI ST BY W QQQ y ATTORNEYS United States Patent 3,138,799 ARRANGEMENT IN SPEAKING RADIO BEACONS Carl-Erik Granqvist, Lidingo, Sweden, assignor to Svenska Aktiebolaget Gasaccumulator, Lidingo, Sweden, a cor- A poration of Sweden Filed Mar. 4, 1958, Ser. No. 719,139 Claims priority, application Sweden Sept. 4, 1957 Claims. (Cl. 343106) So-called speaking radio beacons have hitherto been provided with a rotating antenna system made in such a way that it had a very sharply limited directional characteristic, having a so-called cigar-shaped characteristic. For given angular positions, the prior art speaking radio beacon transmits an indication about the bearing in which the center line of the cigar-shaped characteristic was actually directed, relative to the beacon. A known arrangement of the antenna system contains two antenna systems composed of dipoles mechanically combined with each other, but electrically insulated from each other and having a reflector arranged between said antenna systems.

The spoken sound at each bearing indication will take a given time. This cannot be shortened without the indication losing some of its clearness. Tests made have shown that the time for the spoken bearing indication cannot suitably be made shorter than 0.7 or 0.8 second. For obtaining the desired sharpness in bearing indication this should further be limited to less than a half part of the step between two hearings in which bearing indications following after each other are transmitted, and should preferably not mean more than 35 to 40 percent of this angular distance. The total time for the rotation of the antenna during a bearing indication will therefore be practically two seconds of which 0.7 to 0.8 second is sound carrying and 1.2 to 1.3 seconds are sound free. By this manner the frequency is determined with which the sound indications may be repeated. If the sound indications are made every twentieth degree of bearing, the rotation of the antenna will pass an angle of 20 in 2 seconds and will make all of the 360 turn in 36 seconds. With only one antenna, one should obtain bearing indications every thirty-six seconds, but with the above-mentioned arrangement of two antennas and an intermediate screen, the interval time between two successive bearing indications in a given direction will be reduced to eighteen seconds.

With the increased airplane speeds of recent years, especially those of jet-propelled airplanes, a frequency of one bearing indication every eighteen seconds is too low for reliable landing. It is a problem which the invention seeks to overcome by increasing this frequency without decreasing the time consumed by the spoken sound.

According to a feature of the invention, this problem is solved by arrangements which enable the rotation of the antenna system with a controlled variable speed so that the antenna system is moving with a lower speed when passing any marked bearing, and with a higher speed when passing the interval between two marked bearings. As an example of the speed concerned, it may be assumed that the spoken sound will require a time of 0.7 second and that thereafter the rotational speed of the antenna system is substantially increased so that the antenna system will pass the interval between the two angles between which there is spoken sound occurring in a time of 0.3 second, although this interval with a constant rotational speed of the antenna system has consumed a time of 1.3 seconds. By this novel arrangement, the indication frequency is obviously doubled.

One type of radio beacon already known is regarded as a predecessor of the speaking radio beacons. In this beacon, a frame antenna is used, which was put into rotation, and which transmitted with predetermined spaces of time a statement about the bearing. This arrangement was at a time before one had undamped oscillations at ones disposal, and the arrangement was intended for damped oscillations such as spark telegraphy, and the information about the bearing was also transmitted by means of telegraphic signs. In this known arrangement, it was proposed to keep the frame antenna at a standstill during the transmission of telegraphy, and thereafter quickly transfer it into the next position in which a bearing statement should be transmitted. This took place by mechanical means.

Tests in connection with the making of the present invention have proved that with the demands that must be put on a modern speaking radio beacon, it is not possible to provide mechanical means that accelerate and thereafter retard the antenna system of the speaking radio beacon at such a rate that the bearing statements will be repeated sufficiently often. The problem, solved according to the present invention, is to find a means for causing the concerned acceleration and retardation of the field without the antenna being subjected to too strong acceleration or retardation forces, respectively.

According to the invention, the acceleration and retardation, respectively, will be caused by electrical means.

It is not suitable that any of the antennas of the system should move with constant speed during all of the speaking period and then abruptly increase its rotational speed to move with constant even if higher speed during all of the silent period. The strong accelerations subject the antenna system to too severe mechanical strain, but the change of speed takes place in a relatively continuous Way, adapted to the circumstances.

The invention will be further described below in connection with preferred embodiments in which the rotational speed of the antenna system is mechanically subjected to variations in rotation, and in which such steps are taken in connection with the antenna system that its rotational speed is varied electrically while the mechanical rotational speed is constant.

In the attached drawing, FIG. 1 shows a device for causing an electrical change of speed rotation while maintaining the mechanical speed of the antenna system; and FIG. 2 shows a wiring diagram for a commutator contained in the arrangement according to FIG. 1. FIGS. 3, 4 and 5 are schematic diagrams for explaining the action achieved in the arrangement according to FIGS. 1 and 2. FIGS. 6, 7 and 8 show an arrangement in some respects corresponding to the arrangement according to FIG. 1 but used in an antenna system composed of dipole antennas arranged in circular form and other embodiments of the invention.

In FIG. 1 the antenna system is composed of a first antenna system 10 which is arranged for transmission of the spoken bearing indication, and a second antenna system 11 which is arranged to transmit a covering field of tone modulation during the times when sound modulated transmission from the antenna system does not take place. The two antenna systems are applied on a common rotating shaft 12 which is driven by a motor 17 by means of a gear device and a shaft 16. An output shaft 18 from the gear device 15 drives a sound creating machine 19 which includes a modulator for electric radio frequency current fed from a generator 20.

Modulated sound carrier current from the sound creating machine 19 is fed to a device or commutator 35 for coupling the currents to the antenna systems 10, 11 and causing a displacement of the radiation direction of the created field in relation to the antenna systems, as will be described further. There are two identical devices for coupling the modulation to the antennaone connected into a conduit 36 to the antenna system 11, and the other one connected into a conduit 37 to the antenna system 10. As these two commutators may be identical in construction and operation, it is sufficient to describe one of them in detail which will be done in connection with FIG. 2.

The conduit 38 from the modulator 19 consists of two conductors for the modulated current to be transmitted by the antenna 10, and of two further conductors for the current to be transmitted by the antenna 11 (not shown). According to the above, only the two firstmentioned conductors are to be considered at present, and they are shown in. FIG. 2. They are connected to the midpoints of half-wave conductors 39 and 40, respectively, which are connected together at their adjacent end terminals. The part of each conductor on each side of the connection point is thus one-quarter of a wave length long. It is arranged for coupling according to the principle of the quarter'-of-a-wave-length-switch, each to one of conductors 41 and 42, respectively. The conductor 41 is provided with end terminals 43 and 44, and the conductor 42 is provided with end terminals 45 and 46. The conductors 39' and 40 are supported by a layer of insulating material (not shown) mounted in a guide so that they can be displaced in their ownlongitudinal direction. The displacement is made by means of a bar 47 which is driven from an eccentrically geared point on a wheel 48. This wheel is kept in rotation with a number of revolutions by the gear device 15 corresponding to one turn per bearing indication. If eighteen bearing indications are transmitted during each turn of the common shaft 12, then the number of revolutions of the wheel 48- will be eighteen turns for each turn of the shaft 12.

To further explain the function of this arrangement, reference is made to FIG. 3. The six pairs of dipoles contained in the antenna 10 are indicated by solid lines as the bars 49', 49" 54', 54". The upper bars provided with single primes acted in parallel in equal phase by equally long feeder lines from a collector line 55 and, in a corresponding way, the lower bars provided with double primes are fed from a collector line 56. Actually, these collector lines are not running in parallel to the longitudinal direction of the antenna, but this way of drawing has been used only for amplification purposes. The midpoints on the conductors 55 and 56 are combined with the two conductors 38 and 38", respectively, contained in the conduit 38 to the antenna 10. In the case now shown, the antenna 10' will transmit a field the symmetry axis of which is perpendicular to the plane of the antenna 10, and indicated by means of the arrow 57.

It is now assumed that the connection point of the conductors 38' and 38", respectively, is displaced into a dissymmetrical point on the collector lines 55-, 56 indicated by means of the points 58 and 58-", respectively. The displacement can be calculated into electrical measure or terms as a given number, of degrees, one full wave length of the transmitted signal thereby being calculated as 360. This will cause the directional characteristic of the antenna 10 while maintaining substantially the same form to be displaced, or more correctly, to be turned in the opposite direction a number of degrees essentially equal to the number of electrical degrees of displacement between the connection points for the conductors 38' and 38", respectively. The axial direction of the field lobe can be selectively situated in the direction indicated by means of the arrow 59. It should be noted that the arrows 57 and 59 do not actually fall in the level of the paper in FIG. 3, but that they should more correctly have been situated in a plane substantially perpendicular to the paper in this figure; but for simplification of the drawing, these arrows have been shown in the directions as they appear on the drawing.

The same description applies to the antenna system 11, as is seen from FIG. 4, where the four bars of the antenna have been indicated as 60' and 60", respectively, as well as 61' and 61", respectively. For obtaining the correct direction of the lobes created by this antenna the feeder lines 62 and 63, respectively, are crossed in a way which is seen in the figure. The symmetrical conduits are indicated 64, whereas the assymmetrically applied conduits are indicated 65. When current is fed by means of the conduits 64, the field lobes will get the direction 66; and when current is fed by means of the conduits 65,. the lobes will be turned into the direction 67.

FIG. 5 shows in principle a quarter-of-a-wave-length switch. Two conductors run in parallel with each other along a length of one-quarter of a wave length, such as the conductors 68 and 69 in FIG. 5. One end of each conductor is grounded. If the one conductor 68 is fed with current, a distributed capacity in combination with distributed inductance along the conductors will cause an induction to take place in the conductor 69 with very small losses which will, according to experience, he in the order of magnitude of only 2' to 3 decibels.

Comparing now the principle of the sketch of FIG. 5 with the coupling device according to FIG. 2, it is mediately seen that four quarter-of-a-wave-length switches exist, vis. one between the left half part of the conductor 39 and the part of the conductor 41 abreast therewith,-

one between the right half part of the conductor 39 and the part of the conductor 41 abreast therewith, and in a symmetrical way two couplings between each half part of the conductor 40 and the corresponding parts of. the conductor 42. The division points on the conductor 41 and the conductor 42 should, in order that the similarity to the principle according to FIG. 5 will be complete, be connected to a ground, as indicated by the dotted line ground connection 70. Due to the symmetry relation, this connection can be omitted.

The displacement of the insulating part supporting the conductors 39 and 40 will take place in such a time that the rotation speed of the field is momentarily decreased every time the antenna 10 is transmitting a sound signal, but will thereafter be increased during the intervals between these moments. One will thereby obtain a to-andfro oscillation in a peripheral direction superimposed ontothe rotation of the antenna system but only visible in con nection with the position of the field lobes.

In a copending application,

disclosed for use in connection with speaking directed radio beacons an antenna device kown per se consisting of a number of dipole antennas of vertical direction arranged at equal distances along a circle situated in the horizontal plane, and inside this ring. of these dipole antennas a corresponding ring of reflector bars. Contrary to the above-mentioned antennas, this antenna of the present invention is not rotating but fixed, and the rotation of the field lobe is caused by a commutator device. An antenna of this common type is schematically shown in FIG. 6. I

In this known antenna system there are a number of dipole antennas 71 arranged at equal intervals along a circle and inside of them a corresponding row of eighteen bars forming a reflector 72.

In the use of this known antenna for a speaking radio Serial No. 719,138, there isbeacon, the number of dipole antennas as well as the number of reflector bars may, for instance, be eighteen. The bars 71 are combined with secondary elements 73 in a collector having primary elements 74 which are rotated. The feeding of the dipole antennas with a sound modulated radio frequency current takes place in the arrangement in such a way that with this single antenna system substantially the same field characteristics are obtained as with the antenna system shown in FIG. 1 which contained two antennas arranged at different heights. This is made in such a way that at every successive moment certain dipoles, for instance the dipoles 75 and 76, are connected by means of the commutator element 74 to the transmitter of the sound modulated signal and, simultaneously, the remaining dipoles 77 and 78 are by means of the commutator element 74 connected to the transmitter for the covering field signal.

FIG. 7 shows an arrangement of six dipoles which are contained in the dipole group 75 of FIG. 6, as well as their connections to the commutator and the transmitter.

The six dipoles of FIG. 7 are indicated 79-84. As mentioned above, they are fixed and connected to the six contacts of a rotating commutator. The connection is made by means of coaxial couplings and coaxial cables, an arrangement which has been made with regard to the high frequency of the transferred alternating current. Thus for coupling from parallel conductors to the coaxial cable, a balun 85-90 is provided between each of the six dipoles 79-84 and each of the coaxial cables 91-96. The commutator consists of quarter-of-a-wave switches 97- 102, the secondary bars of which are fixed and the primary bars are rotating. The primary bars of the commutator are connected to collector conductors 103 and 104, corresponding to the collector conductors 55 and 56 in FIG. 3.

By means of a further pair of baluns 111 and 112, collectors 103 and 104 are connected to the conductors 113 and 114, respectively, which lead to a capacitive commutator 115, the input conductors 116 and 117, respectively, being combined by means of baluns 118 and 119 to the signal generator 120.

The capacitive commutator 115 and the commutator constiting of the quarter wave-length conductors 97-102 are mounted on a shaft 121 driven by means of a coggear 122 by a motor 123. The function of the arrangement in the parts now described is briefly that the six dipoles 79-84 transmit a field of a cigar-shaped characteristic in a direction indicated in the manner earlier used which is represented by arrow 124. If the rotation of the two commutators is in a clockwise direction, the axial direction of the characteristic will rotate in clockwise direction synchronously with the rotation of the commutators. By the function of the signal generator 120, the current fed to the dipole antennas is simultaneously modulated with a sound indicating the direction of the axis of the characteristic lobe or, preferably, the contra-bearing to this direction which, in other words, means the bearing onto the beacon from the place where the modulated sound is heard. After rotation of one-eighteenth of a turn, or 20, the dipole 79 will, as a result of the action of the commutator 97-102, have been cut away from the dipole group 75 instead of being contained in the dipole group 77, whereas the dipole 125, FIG. 6, has now been connected into the dipole group 75. A corresponding displacement has taken place between all of the groups 75-78 which means that the total of the directional characteristics have turned 20 in clockwise direction. In this position the next following bearing indication is transmitted.

If the conductors in the quarter-of-a-wave-length switches 97-102 were point-formed, i.e., a conductor having a cross-section represented as a point, which, of course, must be regarded as a purely theoretical assumption since cross-sectional dimensions of conductors are greater than zero, and if they further were placed at the same level,

which is a technical impossibility, then the rotation of the field lobes Would take place entirely uniformly. By the conductors having an extension in a level perpendicular to the level of the FIG. 7, the speed with which the field lobes rotate will be non-uniform or, more precisely, will be of such a kind that the field rotates with a lower speed at the moment when the conductors are radially opposite each other; and with a higher speed when the conductors of the rotor are in the middle of the spacing between two adjacent stator conductors. The action of this will be just such a non-uniformity of the rotation speed of the field lobes which is required according to the present invention. The non-uniformity will in practice be sufi'icient for some purposes but insuificient for many other purposes. It may be increased so that it will assume practically every desired value by broadening either the stator conductors or the rotor conductors in the quarterof-a-Wave-length commutator 97-102 into band-form, as indicated in FIG. 8.

It can be seen that as long as the conductor -110 is at a constant distance from the band-formed conductor 91-96, there is no difference in transferred voltage and, consequently, the field lobe will during that time be momentarily stopped in its rotation. Thereafter, a very rapid rotation of the field lobe will take place so that this field lobe is turned fully 20 during the time when one conductor, for instance the conductor 105, is passing the spacing between two adjacent band-formed stator conductors, for instance the conductors 91 and 92.

The invention is of course not limited to the embodiments described above in specific detail with reference to the drawings, but different modifications may occur within the scope of the invention.

What is claimed is:

1. A speaking radio beacon comprising a signal generator, a dipole antenna system having a first radiation pattern in the shape of a concentrated beam pattern and a second radiation pattern in the shape of a figure 8 pattern with its axis normal to the axis of said beam pattern, means rotating the dipole antenna system at a constant speed for causing a rotation of said radiation patterns, means for applying a bearing identification signal from said signal generator to said antenna system at regular intervals to be transmitted according to said first radiation pattern, and means for decreasing the speed of rotation of said patterns while said bearing identification signal is being transmitted and increasing the speed of rotation of said patterns between tranmission of said bearing identification signal.

2. A speaking radio beacon according to claim 1 wherein said dipole antenna system includes a plurality of dipoles fed by the signal generator in a given phase position and means are provided for displacing said phase position.

3. A speaking radio beacon according to claim 2 wherein said dipoles are arranged in two symmetrical groups, a quarter-wave-length coupling is connected between said signal generator and each of said dipoles of the antenna system, and means are provided for periodic displacement of the phase of the signal fed to each of said groups.

4. A speaking radio beacon according to claim 3 wherein each of said quarter-wave-length couplings comprises four primary quarter-wave-length conductors and four secondary quarter-wave-length conductors, and means are provided for longitudinally displacing said primary conductors relative to said secondary conductors.

5. A speaking radio beacon according to claim 4 wherein each of said secondary conductors are connected to a dipole of one of said groups, and each of said primary conductors are connected to a dipole of the other of said groups.

6. A speaking radio beacon according to claim 1 wherein said dipole antenna system comprises a plurality of dipole elements in parallel and arranged at equal distances 7 about a circle, and a corresponding circle of reflector bars is disposed inside the circle of dipole elements, each of said dipole elements being connected to said signal generator by means of a quarter-wave-length coupling.

7. A speaking. radio beacon according to claim 6 wherein the primary conductors of said quarter-wave-length coupling, are of substantially greater width than the secondary conductors.

References Cited in the file of this patent UNITED STATES PATENTS Jackson Nov. 6 1928 Carter Jan. 30, 1940 Parsberg Oct. 22 1940 Loughren Sept. 3, 1946 Patterson Dec. 3, 1946 Bagnall Apr. 15, 1949 

1. A SPEAKING RADIO BEACON COMPRISING A SIGNAL GENERATOR, A DIPOLE ANTENNA SYSTEM HAVING A FIRST RADIATION PATTERN IN THE SHAPE OF A CONCENTRATED BEAM PATTERN AND A SECOND RADIATION PATTERN IN THE SHAPE OF A FIGURE 8 PATTERN WITH ITS AXIS NORMAL TO THE AXIS OF SAID BEAM PATTERN, MEANS ROTATING THE DIPOLE ANTENNA SYSTEM AT A CONSTANT SPEED FOR CAUSING A ROTATION OF SAID RADIATION PATTERNS, MEANS FOR APPLYING A BEARING IDENTIFICATION SIGNAL FROM SAID SIGNAL GENERATOR TO SAID ANTENNA SYSTEM AT REGULAR INTERVALS TO BE TRANSMITTED ACCORDING TO SAID FIRST RADIATION PATTERN, AND MEANS FOR DECREASING THE SPEED OF ROTATION OF SAID PATTERNS WHILE SAID BEARING IDENTIFICATION SIGNAL IS BEING TRANSMITTED AND INCREASING THE SPEED OF ROTATION OF SAID PATTERNS BETWEEN TRANSMISSION OF SAID BEARING IDENTIFICATION SIGNAL. 